Secondary beta phenyl propyl amines and pharmaceutical compositions thereof



Patented Oct. 13,1942

UNITED STATES PATENT. OFFICE SECONDARY B PHENYL PROPYD AIMINES AND PHARMACEUTICAL COMPOSITIONS THEREOF Robert s. Shelton, Mariemont, om, assignor to The Wm. S. Merrell Company, Cincinnati, I 'Ohio, a corporation of Delaware No Drawing. Application December 24, 1950,

Serial No. 371,574

Claims.

in which Ar is an aryl nucleus with or without attached groups such as OH or -CI-ls, are possessed of vase-constrictor properties. For the most part such compositions are non-volatile,

but the beta-phenyl-isopropyl amines represented by the formula PhCHzCH CH9 NHz, known commercially' as Benzidrene, have substantial volatility at ordinary temperatures; and, largely because cf this, they have come into extensive use in vaso-constrictors, particularly for the shrinking of nasal membranes for treatment of the common cold, hay fever, etc.

Othercompounds which have been studied for their vaso-pressor effect and reported in the literature are the phenyl-ethyl amines, both alpha and beta, and the phenyl-propyl amines, alpha, beta and gamma. Thus, for example, in 1917 a rather extensive study of the pressor action of the amines was reported in the Journal of the Chemical Society, (London) vol. 111, page 103,

et seq. It was there shown that in the homologous series aniline, benzylamine, phenyl-ethyl amine (both alpha and beta), phenylepropyl amine, there is an increasing activity up to phenyl-ethyl amine descreasing again with henyl-propyl amine.

This conclusion confirmed an earier report in the Journal of Physiology, 1910, vol. 41, page 19 et seq. and was in turn confirmed by further investigations of these and related compounds reported in the Journal of the American Chem ical Society in 1931, vol. 53, page 1875 et seq.

andthe similar studies reported in the Journal or Pharmacology in 1929, vol. 36, pages 363 et seq, and in 1933, vol. 47, pages 339 et seq. In these latter publications, however, it was indicated that 59 the addition of a methyl group to one end of the ethyl group in the beta-phenyl-ethyl amine did not noticeably impair the pressor effect. Nevertheless, it was observed by these investigators and tertiary amines.

in general, such increases in molecular weight result in significant increases in toxicity,

It was also brought out by these investigators that the change from the ethyl to propyl compounds of this type, if by addition of a methyl group to one end of the ethyl chain without altering the relative positions of the amino and phenyl groups prolongs the vaso-pressor eiiect without increasingits intensity. The logical in- 10 ie'renc'e from all this experience and evidence is that the beta-phenyl-isopropyl amine compounds are the optimum compounds of this type; and this clear inference has discouraged further modifications oi the basic chemical structure by 15 substitution thereon of methyl or other hydrocarbon groups.

The secondary and tertiary amines formed by adding methyl or ethyl groups to the amino nitrogen of c-phenyl-ethyl-amine and various by- 29 droxy amines analogous to ephedrine have also been made and tested for their physiological properties, with the conclusion that primary amines tend to be more active and less toxic than corresponding methylated secondary and (Hartunget al. J. A. C. S. 53 (1931) 4149 and Pyman J. Chem. Soc. (London) 111 (1917) i103, 1122 quoting Berger 8: Dale J. Physiol. 41 (191%) 19.

It is also known that, in general, an increase 39 in molecular weight in such an homologous series I is accompanied by a decreasein volatility.

I have now found, however, contrary to all indications of the prior art, that the novel amine and amine. salts, the beta-phenyl-beta-methylalpha- (substitute domino) ethanes on-onr-Nn n wherein R is methyl, vinyl or allyl, although they are of higher molecular weight than the beta-phenyl-isopropyl amine compounds and al- 45 though they are secondary amines, exhibit surprising physiological activity. particularly as vaso-constrictors: and they are less toxic than, for example, other similar compounds of comparable activity. In addition certain of these compounds, especially the free amines, and salts of weak acids, show surprising volatility, which is of great advantage when such compoimd is'used as an inhalent.

Comparative tests, for example on rabbits, with has been confirmed by the present applicant that, intravenous injection of -'d,l-beta-phenyi-betabe from less than V:

examples of my invention methyl-alpha-(methyl-amino) ethane hydrochloride of the present invention showed a minimum lethal dose of 60 mg. per kg. of body weight, whereas under the same'conditions corresponding d,l-beta-phenyl-isopropyl amine hydrochloride showed a minimum lethal dose of 20-25 mg. per kg. of body weight, 1. e., the compound oi 'my invention is shown by this'test to down to one-third astoxic as the corresponding phenyl-isopropyl amine compound. With the free amine of the present invention, a vapor pressure of 1 mm. is reached at 65 F., whereas the same pressure is reached by the d,l-beta-phenyl-isopropyl amine at 50. Corresponding comparative tests with these two compounds show that, both in their shrinking of the nasal mucosa and in blood pressure rise, they exhibit substantially the same physiological activity.

Compared also with the corresponding primary amine compounds differing only in the absence of the substituent group on the amino nitrogen, the compounds of my present invention are more active and less toxic. Surprisingly, although the methyl amino compounds are less volatile inhalents, i. e., for application to nasal mucosa by, drawing the breath over a mass of the-volatile compound absorbed in a cotton pad. Contrary to expectation also the free amine is water soluble, which may account in part for its surprising efiectiveness in vapor application to mucous mebrane.

The racemic compound may be resolved into the respective isomers in the usual manner.

The racemic compounds exhibit both vaso constrictor and stimulant action, but upon separationof the optical isomers it is found that the vaso constrictor action is stronger in the laevo isomer and the toxicity less, whereas the dextro isomer is more effective as a central stimulant, and whereas in other related compounds such as ephedrine the laevo isomer is the more toxic, in this case the relative toxicity is reversed, the laevo isomer here being of surprisingly low toxicity: The isomers, however, and the method of preparation are claimed in companion applications.

The allyl amino and vinyl amino compounds are close to the methyl amino compounds in their physiological properties.

Although I am giving below certain specific and its application in practical use and am giving also certain modifications and alternatives, it should be understood that these are not intended to be exhaustive or limiting the invention. On the contrary I am giving these as illustrations and am giving herewith explanations in order fully to acquaint others skilled in the art with my invention and the principles thereof and a suitable manner 'of its application in practical use, so that others skilled in the art may be enabled to modify the invention and to adapt it and apply it in numerous forms each as may be best suited to the requirements of a particular use.

The compounds of the present invention may be prepared, for example, as follows:

A mixture of 100 grams of B-phenyl-n-propyl chloride and approximately 50 grams of monomethylamine are dissolved in a suitable organic solvent such as 150 cc. of methyl alcohol and reacted under pressure with heat for a number of hours in an oil bath or electrically heated container to about 130 C. The container is then cooled in ice and opened carefully to remove the 7 reaction mixture. The reaction mixture is then warmed slightly to remove the unreacted monomethylamine and the product subject to distillation under vacuum. The purified material boils at 99--100 C. at 19 mm.

The corresponding allyl amino and vinyl amino compounds may be made by the same method using allyl amine and vinyl amine respectively.

The compounds of my invention may b made by other methods already known for synthesis of related compounds, e. g., by methylation, vinylation or allylation of the corresponding primary amine by methyl, vinyl or allyl chloride; or by reacting the primaryamine with formaldehyde, vinyl aldehyde or propenyl aldehyde in the presence of hydrogen or other reducing agent.

The beta-phenyl-beta-methyl-alpha (substituted amino) ethanes of the present invention may be used as a free amine or as a salt formed by combination with any suitable acid radical. Where the compound is to be used in a volatile nasal inhalent, i. e., by drawing the breath over a supply of the volatile pressor compound so as to pick up an effective concentration of vapor before passing into the nostril, the free base or salts of weak acids, e. g., the carbonates, will be chosen because of their relatively high volatility. Ordinarily the free amine will be used to charge the inhaler tube, but this may react with the air the compound actually applied to the nasal mucosa. Where the compound is to be used for topical application, e. g., as in nose drops or sprays, or for oral administration, other salts may be used in substance or in solution or in mixture with other ingredients. For this purpose the levulinate has been found most advantageous in its physiological action, but the sulfate and hydrochloride have also been found suitable and easy to prepare. It will be understood that the acid radical may have an influence on properties other than volatility, e. g., toxicity, solubility, stability, cost of manufacture, etc., and I have also found that the vaso-pressor properties of amines of this type can be combined with physiological properties of an acid radical, as for example the salt of acetyl salicylic acid with the amine of this invention may be used to combine the physiological activities of the acid with that of the amine. The antipyretic activity" of the salicylate can be combined with the action of the amine on uterine muscle which lends itself to treatment of certain. conditions such as dysmenorrhea. In general where the physiological properties of only the amines are desired and 'the highest volatility is not required I have found that the levulinate is best.

As an example of the use of these materials, a composition particularly suitable for use as a nasal inhalent may be made as follows:

Part:

Menfhnl Camphor l Beta-phenyl-beta-methyl-alpha m e t h y 1 amino) ethane (as the free amine) 8 of rose, etc. The proportion of amine may bei 5 increased or decreased if desired.

to form the carbonate, which may thus become be made as follows:

A material suitable for useas nose drops may The sorbitol is added to make the product isotonic. The pH of the solution isadjusted to approximately 7. The surface tension 'of this Parts Beta-phenyl-beta-methyl alpha (methyl amino) ethane levulinate 0.4

Butyl para-hydroxy benzonate Syrup of raspberry, to make 100.0

The sulfate radical of the amine salt may bereplaced by any other suitable anion such as sulfate, phosphate, halide, ascorbate, etc. the butyl para-hydroxy benzoate may be replaced by a suitable quantity of any other preservative such as 1 sodium benzoate, alcohol, etc.; and the raspberry syrup may be replaced by any other palatable flavoring syrup or elixir and further sweetened,

or otherwise modified if desired, by-an agent such as saccharin, extract of glycyrrhiza, etc. Alternatively, the amine salt may be mixed with a material is 34.5 dynes per square centimeter which probably accounts at least in part for its very quick action, e. g., as compared with correspondingephedrine sulfate preparations. We prefer to use organic acid salts rather than mineral acid salts since they are less irritating.

The use of sorbitol in this manner and also the I use of a surface tension depressant (cetyl pyridinium chloride serves this function as well as being strongly germicidal) has important advantage even when used with other types of vas0-' pressors, e. g., ephedrine or benzidrene, etc.

Oil vehicle nose drops may be made asfollows:

Parts amino) ethane Oil of eucalyptus 1.0 Mineral oil to make 100.0

The free amine may be replaced by any of its oil-soluble fatty acid salts such as the oleate, palmitate, etc.; the oil of eucalyptus may be replaced by any of those aromatics commonlyused in nose drops such as varying proportions of Beta-phenyl-beta-methyl-alpha I; (methylmenthol, camphor, thymol, etc.; and the mineral oil may be replacedby a vegetable oil such as peanut oil, cottonseed oil, sesame oil,- etc.

Another suitable preparation in an aqueous vehicle may be made according to the formula:

Parts Beta-phenyl-beta-methyl-alpha (methyl amino) 'ethanesulfate-.. Menthol Sodium chloride Chlorbutanol 0.5 Distilled water to make 100.0

' .The amine sulfate may be replaced by any other water-soluble acid addition salt of the free amine such as the phosphate, hydrochloride, etc., or the water-soluble organic salts, or by the free amine; the menthol may be replaced, by a suitphenyl-beta-methyl-alpha-(allyl tures of them.

' methyl, vinyl and allyl. 2. The chemical compounds beta-phenyl-betamethyl-alpha-(methyl amino) ethanes.

' methyl-alpha-(vinyl amino) ethanes.

4. The chemical compounds beta-phenyl-beta=- able quantity of any other aromatic or combination oiaromatics such as methyl salicylate, oil of spearmint, etc.; the sodium chloride may be replaced by any other substance such as dextrose to impart tonicity or by suitable quantities of buffer salts such as phosphates of sodium to adjust the pH; the chlorbutanol may be replaced by any other suitable preservative; agents such as gums, tragacanth,karaya and the like may be. a

used to impart viscosity and thus promote retention of the medicament in the nostrils, and the composition may if desired be supplied as a Jelly.

For oral administration, for example, for control of blood pressure, a composition such as the "following would be suitablei.

V methyl-alpha- (methyl amino) ethane.

amino) ethanes having the formula prises as active ingredient therein at least one of suitable diluent such as lactose, granulated and compressed into tablets for oral administration.

I use the plural form beta-phenyl-betamethyl-alpha-(substituted aminob-ethanes" and specifically beta-phenyl beta: methyl alpha- (methyl amino) -ethanes," beta-ph'enyl-betamethyl-alpha-(vinyl amino) -ethanes and betaanes" to include the free amines specified and their salts andjthe optical isomers as well as mix- What I claim is:

1. The chemical compounds beta-phenyl-betamethyl-alpha -(substituted amino) ethanes having the formula 1 wherein R is a radical of the group consisting of 3. The .chemical compounds beta-phenyl-betamethyl-alpha-(allyl amino) ethanes.

5. The chemical compound beta-phenyl-beta- 6. The chemical compounds beta-phenyl-betamethyl-alpha-(methyl amino) ethane salts.

, I. A vase-constrictor composition which cornpri'ses as active ingredient therein at least one of the beta-phenyl-beta-methyl-alpha- (substituted wherein R is a radical of the group consisting of methyl, vinyl and 9.1131. I

8. A vase-constrictor composition which comt h e beta-phenyl-beta-methyl alpha (methyl amino) 'ethanes.

' 9. A vase-constrictor composition which com-' prises as active ingredient therein at least one of the beta phenyl beta methyl 9 alpha (vinyl amino) ethanes.

10. A vaso-constrictor composition which comprises as active ingredient therein at least one: the beta phenyl beta methyl alpha (allyl amino) ethanes.

, ROBERT S. SHELTON.

amino) -eth- 

